In the scene introducing Victor Buono, he immediately tells Davis that he is a homosexual (something about which the real Buono was extremely discreet - understandably in 1962) and is described by Aldrich as an eminent Broadway actor. In reality, Buono was a 23-year-old actor in his first major part who had appeared in regional theater, but would not make his only Broadway appearance until 1970.
Hedda Hopper tells Robert Aldrich that he has had "three flops in a row" and thus must have a success with "Baby Jane" if he wants to continue working. In fact, Aldrich had had five consecutive box-office failures before making "Baby Jane", according to his interview with Peter Bogdanovich in the book, "Who The Devil Made It?" However, he was still able to set up his own projects.